1. Field of the Invention
The present invention relates to a moving picture reproducing device and particularly to an MPEG (Moving Picture Experts Group) moving picture reproducing module.
2. Description of the Related Art
Conventionally, an MPEG moving picture reproducing module, which can be incorporated as a module as part of a whole system, is used in a moving picture producing device for a particular data stream, as illustrated in FIG. 1. Due to a preference for compactness of such modules, there is typically limited memory made available and the modules typically operate at a low cycle speed for low power consumption. The particular data stream is generated by a moving picture generating device (moving picture generating device A in FIG. 1) which generates the data stream with an ISO control code (control code structure A in FIG. 1) having a particular arrangement. Such MPEG moving picture reproducing modules may be realized, for example, as software, recorded on media as computer readable code, incorporated in a larger recording and/or reproducing apparatus, or encapsulated as a standalone MPEG reproducing device.
MPEG moving picture reproducing modules conventionally define a particular data stream as a reproduction object. MPEG moving picture reproducing modules do not analyze data streams based on the ISO control code, but rather base the reproduction of the data stream on expected particular arrangements of a data stream frame ISO control code which is anticipated to be received. Therefore, the MPEG moving picture reproducing modules can be encapsulated as compact software or elements, e.g., a arithmetic device, memory device, or the like).
As noted above, in such MPEG moving picture reproducing modules a data stream is generally defined as a reproduction object, with the data stream also including a picture size of one frame, frame rate, M value (appearing pattern period of key frame), N value (appearing pattern period of both-way reference frame) and insertion interval of PTS (Presentation Time Stamp) code, which is the synchronous output control code described with a particular pattern.
Meanwhile, according to the ISO standard, an ISO control code (parameter) such as the picture size, frame rate, M value, N value and PTS can be set freely within a range of values specified by the ISO standard. Thus, a multipurpose MPEG moving picture reproducing device as illustrated in FIG. 2 reproduces data streams in which the ISO control code of each data stream can have different structures. The multipurpose MPEG moving picture reproducing device analyzes the data stream based on the ISO code and stacks the information obtained by the analysis in an information table in a predetermined memory space. Thereby, the moving picture reproducing device can realize the reproducing function of the different data streams.
In order to execute each operation, such as the analysis of a data stream and stacking of information described above, a more sophisticated resource, e.g. arithmetic device, memory device or the like, is used. Therefore, the reproducing function for differing data streams is generally realized in a device that includes an arithmetic device that can be operated at a high speed operation cycle and a memory that has sufficient capacity to stack information for the whole data stream, for example, a personal computer.
In addition, Japanese Patent Publication No. Hei 11-355728 discusses an audio/video synchronous reproducing process and discloses a technique for calculating a frame rate of video data using the PTS code without using the frame rate described in the video data.
Typically, in a reproducing operation where the reproducing process starts from an intermediate seek position, rather than the leading position of the data stream, the MPEG moving picture reproducing device typically executes the following processes.
First, the MPEG moving picture reproducing device will sequentially decode all continuous MPEG moving picture data from a leading position of the data stream while buffering such data in a memory device. In this case, the video data and audio data obtained as a result of a decoding process, up to the desired intermediate seek position from which the reproducing process is preferentially to be started, are not outputted, but rather merely rejected.
Next, when the decoding process reaches the predetermined intermediate seek position, the output of the reproduced video data and audio data, obtained as a result of the decoding process, is initiated. In this manner, the reproducing process is executed from the intermediate seek position of the data stream.
However, execution of this intermediate seek position reproducing process requires a decoding process of all continuous MPEG moving picture data from the leading position of a data stream. Therefore, such a process requires a large mount of data to be processed by the arithmetic device, within a certain period, and requires a large amount of data to be buffered by the memory device. Accordingly, a more sophisticated resource (arithmetic device, memory device or the like) must be used.
Therefore, MPEG moving picture reproducing devices which can perform such intermediate seek position reproduction processes generally require high speed arithmetic devices and large capacity memory devices, which have sufficient capacity to simultaneously buffer a large amount of data, for example a personal computer. Thus, there is a need for a MPEG moving picture reproducing device performing such functions while only requiring a limited memory capacity and a lower speed arithmetic device.